I want to do exercise.. But when i start running, my heartbeat start to be more rapid which is usual But As the heartbeat increases while running, I start fearing and i feel like panic attack will come. Because In my history ,i had many panic attacks. So should I keep running or do other exercises? . My main problem is I don't hv that brain power to handle things. I can easily handle anything but when I start thinking and back of the head starts to be heavy and aching.